Rainbow Electronics RF02 User Manual

RF02

RF02 Universal ISM Band
FSK Transmitter

DESCRIPTION

Hope’s RF02 is a single chip, low power, multi-channel

FSK transmitter designed for use in applications requiring

FCC or ETSI conformance for unlicensed use in the 433, 868,

and 915 MHz bands. Used in conjunction with RF01, Hope’s

FSK receiver, the RF02 transmitter produces a flexible, low

cost, and highly integrated solution that does not require

production alignments. All required RF functions are

integrated. Only an external crystal and bypass filtering are

needed for operation. The RF02 offering a higher output

power and an improved phase noise characteristic.

The RF02 features a completely integrated PLL for easy

RF design, and its rapid settling time allows for fast frequency hopping, bypassing multipath fading and

interference to achieve robust wireless links. In addition, highly stable and accurate FSK modulation is

accomplished by direct closed-loop modulation with bit rates up to 115.2 kbps. The PLL’s high resolution

allows the use of multiple channels in any of the bands.

The integrated power amplifier of the transmitter has an open-collector differential output that directly

drive a loop antenna with programmable output level. No additional matching network is required. An

automatic antenna tuning circuit is built in to avoid costly trimming procedures and de-tuning due to the

“hand effect”.

For low-power applications, the device supports automatic activation from sleep mode. Active mode

can be initiated by several wake-up events (on-chip timer timeout, low supply voltage detection).

RF02

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RF02

FEATURES

 Fully integrated (low BOM, easy design-in)

 No alignment required in production

 Fast settling, programmable, high-resolution PLL

 Fast frequency hopping capability

 Stable and accurate FSK modulation with programmable deviation

 Programmable PLL loop bandwidth

 Direct loop antenna drive

 Automatic antenna tuning circuit

 Programmable output power level

 SPI bus for applications with microcontroller

 Clock output for microcontroller

 Integrated programmable crystal load capacitor

 Multiple event handling options for wake-up activation

 Wake-up timer

 Low battery detection

 2.2V to 5.4V supply voltage

 Low power consumption

 Low standby current (0.3 μA)

 Transmit bit synchronization

TYPICAL APPLICATIONS

 Remote control

 Home security and alarm

 Wireless keyboard/mouse and other PC peripherals

 Toy control

 Remote keyless entry

 Tire pressure monitoring

 Tel e m et ry

 Personal/patient data logging

 Remote automatic meter reading

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RF02

DETAILED FEATURE-LEVEL DESCRIPTION

The RF02 FSK transmitter is designed to cover the unlicensed frequency bands at 433, 868, and

915 MHz. The device facilitates compliance with FCC and ETSI requirements.

PLL

The programmable PLL synthesizer determines the operating frequency, while preserving accuracy

based on the on-chip crystal-controlled reference oscillator. The PLL’s high resolution allows the usage of

multiple channels in any of the bands. The FSK deviation is selectable (from 30 to 210 kHz with 30 kHz

increments) to accommodate various bandwidth, data rate and crystal tolerance requirements, and it is

also highly accurate due to the direct closed-loop modulation of the PLL. The transmitted digital data can

be sent asynchronously through the FSK pin or over the control interface using the appropriate

command.

RF Power Amplifier (PA)

The power amplifier has an open-collector differential output and can directly drive a loop antenna

with a programmable output power level. An automatic antenna tuning circuit is built in to avoid costly

trimming procedures and the so-called “hand effect.”

Crystal Oscillator

The chip has a single-pin crystal oscillator circuit, which provides a 10 MHz reference signal for the

PLL. To reduce external parts and simplify design, the crystal load capacitor is internal and

programmable. Guidelines for selecting the appropriate crystal can be found later in this datasheet.

The transmitters can supply the clock signal for the microcontroller, so accurate timing is possible

without the need for a second crystal. When the chip receives a Sleep Command from the microcontroller

and turns itself off, it provides several further clock pulses (“clock tail”) for the microcontroller to be able to

go to idle or sleep mode. The length of the clock tail is programmable.

Low Battery Voltage Detector

The low battery voltage detector circuit monitors the supply voltage and generates an interrupt if it

falls below a programmable threshold level.

Wake-Up Timer

The wake-up timer has very low current consumption (1.5 uA typical) and can be programmed from

1 ms to several days with an accuracy of ±5%.

It calibrates itself to the crystal oscillator at every startup, and then every 30 seconds. When the

oscillator is switched off, the calibration circuit switches on the crystal oscillator only long enough for a

quick calibration (a few milliseconds) to facilitate accurate wake-up timing.

Event Handling

In order to minimize current consumption, the device supports sleep mode. Active mode can be

initiated by several wake-up events: timeout of wake-up timer, detection of low supply voltage or through

the serial interface.

If any wake-up event occurs, the wake-up logic generates an interrupt, which can be used to wake

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RF02

up the microcontroller, effectively reducing the period the microcontroller has to be active. The cause of

the interrupt can be read out from the transmitters by the microcontroller through the nIRQ pin.

Interface

An SPI compatible serial interface lets the user select the operating frequency band and center

frequency of the synthesizer, polarity and deviation of FSK modulation, and output power level. Division

ratio for the microcontroller clock, wake-up timer period, and low battery detector threshold are also

programmable. Any of these auxiliary functions can be disabled when not needed. All parameters are set

to default after power-on; the programmed values are retained during sleep mode.

PACKAGE PIN DEFINITIONS

Pin type key: D=digital, A=analog, S=supply, I=input, O=output, IO=input/output

PinP Name Type Function

1 SDI DI Data input of serial control interface

2 SCK DI Clock input of serial control interface

3 nSEL DI Chip select input of serial control interface (active low)

4 CLK DO Microcontroller clock (1 MHz-10 MHz)

5 XTL AIO Crystal connection (other terminal of crystal to VSS)

6 VSS_D S Digital VSS(Connect to VSS)

7 VSS_A S Analog VSS(Connect to VSS)

8 VSS_RF S RF VSS(Connect to VSS)

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RF02

9 MOD DI Connect to logic high

10 RFN AO Power amplifier output (open collector)

11 RFP AO Power amplifier output (open collector)

12 nIRQ DO

13 VDD_RF S RF VDD(Connect to VDD)

14 VDD_A S Analog VDD(Connect to VDD)

15 VDD_D S Digital VDD(Connect to VDD)

16 FSK DI Serial data input for FSK modulation

Interrupt request output for microcontroller (active low) and status read output

Typical application

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RF02

GENERAL DEVICE SPECIFICATION

All voltages are referenced to Vss, the potential on the ground reference pin VSS.

Absolute Maximum Ratings (non-operating)

Symbol Parameter Min Max Units

Vdd Positive supply voltage -0.5 6.0 V

Vin Voltage on any pin except open collector outputs -0.5 Vdd+0.5 V

Voc Voltage on open collector outputs -0.5 6.0 V

Iin Input current into any pin except VDD and VSS -25 25 mA

ESD Electrostatic discharge with human body model 1000 V

Tst Storage temperature -55 125

Recommended Operating Range

Symbol Parameter Min Max Units

Vdd Positive supply voltage 2.2 5.4 V

Voc Voltage on open collector outputs (Max 6.0 V) Vdd - 1 Vdd + 1 V

Top Ambient operating temperature -40 85

℃

℃

ELECTRICAL SPECIFICATION

(Min/max values are valid over the whole recommended operating range, typ conditions:

Top =27℃;Vdd =Voc=2.7V)

DC Characteristics

Symbol Parameter Conditions/Notes Min Typ Max Units

mA

mA

)

433 MHz band

868 MHz band

915 MHz band

433 MHz band

868 MHz band

915 MHz band

I

dd_TX_0

I

dd_TX_PMAX

Ipd Standby current in sleep mode

Iwt Wake-up timer current

Ilb Low battery detector current

Supply current

(TX mode,

Pout =0dBm)

Supply current

(TX mode,

Pout =P

(Note 1)

consumption

consumption

max

Active state with

0dBm

output power

Active state with

maximum output

power

All blocks

disabled

1.5 µA

0.5 µA

12

14

15

21

23

24

0.3 µA

Ix Idle current Only crystal

oscillator is on

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1.5 mA

RF02

V

lba

Vlb Low battery detector threshold Programmable in

Low battery detection accuracy 75 mV

2.2 5.3 V

0.1 V steps

Vil Digital input low level 0.3*VddV

Vih Digital input high level 0.7*Vdd V

Iil Digital input current V

Iih Digital input current Vih = Vdd, Vdd = 5.4

= 0 V -1 1 µA

il

-1 1 µA

V

Vol Digital output low level Iol = 2 mA 0.4 V

Voh Digital output high level Ioh = -2 mA Vdd-0.4 V

AC Characteristic

Symbol Parameter Conditions/Notes

ref

PLL reference

frequency

f

Crystal operation mode is

parallel (Note 2)

433MHz band, 2.5kHz

resolution

f

o

868MHz band, 5.0kHz

resolution

915MHz band, 7.5kHz

resolution

Min Typ Max

9 10 11

430.24

860.48

900.72

439.75

879.51

929.27

Units

MHz

MHz

P

P

t

lock

t

I

OUT

maxL

maxH

P

P

PLL lock time

PLL startup time

sp

Open collector output

current (Note 3)

Available output power

(433MHz band)

Available output power

(868 and 915 MHz

band)

Typical output power

out

Spurious emission

sp

Frequency error < 10 kHz after

10 MHz step, POR default PLL

setting(Note 7)

After turning on from idle

mode, with crystal oscillator

already stable, POR default

PLL setting (Note 7)

At all bands

With opt. antenna impedance

(Note 4)

With opt. antenna impedance

(Note 4)

Selectable in 3 dB steps (Note

3)

At max power with loop

antenna (Note 5)

20

250

0.5 6

8

6

P

-21 P

max

max

-50

µs

µs

mA

dBm

dBm

dBm

dBc

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RF02

BR

C

Q

L

df

C

t

POR

t

Output capacitance

(set by the automatic

o

At low bands

At high bands

1.5

1.6

2.3

2.2

antenna tuning circuit)

Quality factor of the

o

output capacitance

Output phase noise

out

FSK bit rate (Note 7) 115.2 kbps

FSK

FSK frequency

fsk

deviation

Crystal load

capacitance See

xl

Crystal Selection

16 18 22

100 kHz from carrier

1 MHz from carrier (Note 7)

Programmable in 30 kHz steps

Programmable in 0.5 pF steps,

-85

-105

30 210

8.5 16

tolerance +/-10%

Guidelines

Internal POR timeout

(Note 6)

Crystal oscillator

sx

startup time

After Vdd has reached 90% of

final value

Crystal ESR < 100 Ohms

50

1.5 5

2.8

3.1 pF

pF

dBc/Hz

kHz

pF

ms

ms

t

PBt

t

wake-up

C

in, D

t

r, f

Wake-up timer clock

period

Programmable

wake-up time

Digital input

capacitance

Digital output rise/fall

time

Calibrated every 30 seconds

1 5 *10

2

15 pF pure capacitive load

0.95 1.05

11

10

ms

ms

pF

ns

Note 1: Using a CR2032 battery (225 mAh capacity), the expected battery life is greater than 2 years

using a 60-second wake-up period for sending 50 byte packets in length at 19.2 kbps with +6 dBm output

power in the 915 MHz band.

Note 2: Using anything but a 10 MHz crystal is allowed but not recommended because all

crystal-referred timing and frequency parameters will change accordingly.

Note 3: Adjustable in 8 steps.
Note 4: Optimal antenna admittance/impedance for the RF02:

Yantenna [S] Zantenna [Ohm] Lantenna [nH]

434 MHz 1.3E-3 - j6.3E-3 31 + j152 58.00

868 MHz 1.35E-3 - j1.2E-2 9 + j82 15.20

915 MHz 1.45E-3 - j1.3E-2 8.7 + j77 13.60

Note 5: With selective resonant antennas .
Note 6: During this period, no commands are accepted by the chip.
Note 7: The maximum FSK bitrate and the Output phase noise are dependent on the actual setting of the

PLL Setting Command.

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